What is External Ear Aural Atresia?
Aural atresia refers to the condition where the ear canal is not open or formed properly. This condition can be developed later in life, often due to inflammation, injury, or the result of ear surgery, or it can be present at birth. In the cases where it is present from birth, this is a defect of the external ear canal which leads to serious hearing loss in newborns and continues into their later years. For these individuals, the middle ear may either be perfectly normal or also have similar deformities.
The human ear consists of inner, middle, and outer parts. The outer ear, which includes the auricle (also known as the pinna) and the external ear canal, plays a vital role in hearing as it helps guide sound waves to the eardrum and the middle ear. Interestingly, even if the pinna is lost, a person can still hear normally. The pinna is also important structural support for wearing hearing aids and glasses, if needed.
From a biological viewpoint, the external ear forms from particular structures during fetal development known as the first pharyngeal cleft and the first and second pharyngeal arches. In some instances, remnants of these developmental structures can continue to exist after birth as cysts or abnormal tunnels that can cause problems if they become infected. So, any failures in incorporating these structures during development in the womb lead to external ear deformities and hearing loss. The extent of these deformities can range from narrowed ear canals (less than 4mm in diameter) to completely closed ear canals. This often occurs alongside microtia, a deformity of the auricle. Very rarely, this may occur on both sides or with other symptoms as part of a syndrome. Doctors use something called the Jahrsdoerfer grading scale to decide if surgery is appropriate and to anticipate outcomes for these patients.
What Causes External Ear Aural Atresia?
Acquired aural atresia, a condition where the ear canal is blocked or absent, though rare, can often occur after damage to the external ear. This can result from things like car accidents, gunshot wounds, or ear surgery. In some rare cases, blockages in the ear canal or complete absence of it can occur due to cancerous changes or unexplained inflammation.
The exact cause of congenital aural atresia, which means someone is born with it, can depend on many factors. It can result from disruption during the early stages of the baby’s development in the womb, which affects the growth of the external auditory canal. There are several syndromes linked with this condition, including Goldenhar, Treacher Collins, and Crouzon. With Goldenhar syndrome, it’s believed that the cause is an early issue with the development of the first and second parts of the baby’s neck, known as “pharyngeal arches”, in the womb. This condition often affects the right ear and may include issues with the eye socket, lower jaw, spine, or other parts of the face and head.
Some of these conditions may follow a pattern where they are passed down through families, potentially due to multiple changes in genes. For example, Treacher-Collins syndrome, associated with aural atresia, is often caused by changes in the TCOF1 gene, which is involved in the early development of the face and pharyngeal arches. Crouzon syndrome, caused by changes in the FGFR2 or FGFR3 gene, is also passed down in families and can often cause craniosynostosis (a condition where the bones in a baby’s skull join together too early) and occasionally cause aural atresia. Other conditions like Mobius, Klippel-Feil, Fanconi, DiGeorge, and Pierre Robin syndromes can also involve aural atresia.
There’s only one known specific genetic cause of congenital aural atresia that’s not linked with any effects on other body parts. This is a deletion in the distal 18q22.3 part of our genetic code. With this specific genetic change, the child will have normal outer ears and complete aural atresia on both sides and other typical facial abnormalities.
Several external risk factors include certain medications used by the mother like isotretinoin and thalidomide, issues with blood supply to the developing baby often because the mother used cocaine, and diabetes in the mother during pregnancy.
Risk Factors and Frequency for External Ear Aural Atresia
Congenital aural atresia, or a birth defect in which the ear canal is absent, happens in about 1 out of 10,000 to 20,000 births. It usually affects just one ear, most often the right, and is 2.5 times more likely to happen in males than females. This condition often comes with varying degrees of microtia, where the external ear is underdeveloped; this could be related to the severity of the middle ear deformation.
Children with this condition in only one ear usually have normal speech development, provided that their other ear is unaffected. They also typically have normal hearing in the unaffected ear. However, these children may have a higher risk of delayed language development due to limited hearing, so it’s important to identify this early. To promote normal language development, they are often positioned or seated in a way that maximizes the use of the unaffected ear, such as directing the unaffected ear towards the teacher during school.
- Congenital aural atresia, a birth defect where the ear canal is missing, occurs in about 1 of every 10,000 to 20,000 births.
- It usually affects one ear, most commonly the right one.
- It’s 2.5 times more likely to occur in males than females.
- This condition often comes with an underdeveloped outer ear, which could correlate with the abnormality of the middle ear.
- If only one ear is affected, the child usually has normal speech development if the other ear is unaffected.
- These children also typically have standard hearing in the unaffected ear.
- They may be at a higher risk for delayed language development due to decreased hearing, making early identification crucial.
- Promoting normal language development often involves positioning or seating them in a way that maximizes the use of the unaffected ear.
Signs and Symptoms of External Ear Aural Atresia
Acquired aural atresia is a condition usually noticed when a person experiences a gradual loss of hearing, and the ear canal visibly appears narrower. This is usually identified through a detailed physical examination to check for any local inflammation that might be causing the ear canal to constrict or develop fibrous tissue. If the person also has a history of ear trauma, repeated outer ear infections, or ear surgery, it could offer clues to the root cause. In the absence of these factors, doctors may investigate to see if it could be due to an unknown autoimmune condition.
On the other hand, congenital aural atresia, a condition that a baby is born with, can be suspected during the first few days after childbirth. As part of the initial examination, doctors thoroughly check the baby’s external ear, jaw, oral cavity, spine, eyes, and facial nerve function. Generally, a baby with this condition may have an underdeveloped ear which may appear small or absent, and the ear canal may also be constricted, shortened, or missing. Other features outside the skull, like the nerves and joints, should also be checked. If a baby fails their newborn hearing test, the doctors will do a more extensive examination to ensure the ear canals are not blocked. This can be difficult to carry out on a newborn, so if there are any concerns, they should be promptly referred to a pediatric ear, nose, and throat specialist.
Testing for External Ear Aural Atresia
Any child born with an ear deformity should receive thorough hearing tests within the first few months of life. The first step usually involves ‘auditory brainstem response testing’, which is a test that checks how the inner ear, called the cochlea, and the brain pathways for hearing are working. This test is necessary because hearing loss can occur in one or both ears. It helps determine whether the patient lacks the ability to conduct sound or has damage to the nerve that sends sound to the brain. While it is generally observed that most hearing loss in patients with ear deformities is due to the former, up to 15% do have the latter, which would require a more in-depth examination.
If the health check shows normal hearing in the unaffected ear, the child is likely to develop speech and language skills normally, therefore further testing can be postponed till the child turns six months old. However, regardless of the result, regular check-ups and immediate treatment of any fluid build-up in the middle ear is critical to maintain normal hearing in the unaffected ear.
If the hearing test shows abnormal results, auditory brainstem response testing is again necessary to ensure at least one ear is functioning properly and would support normal language development. In some cases, the child might need genetic testing, if the doctors suspect their conditions to be part of a syndrome. A specific type of CT scan, called a ‘temporal bone computed tomography scan’, is generally not needed in the initial assessment until the child is five years old or when surgery is required. This decision might rely on the ‘Jahrsdoerfer grading scale’, a scoring system that looks for certain features in the ear to predict whether surgery would be effective or not. The scale assigns points based on the presence of specific parts of the ear, and the total score can go up to 10 points. The higher the score, the better the chances for successful surgery.
Treatment Options for External Ear Aural Atresia
The best approach for treating a condition where the ear canal doesn’t fully develop, known as acquired aural atresia, is a surgery. However, how to handle the early stages isn’t agreed upon. Some ear specialists suggest treatment with antibiotics and anti-inflammatory medications, but others express concern that delaying surgery can cause the condition to worsen. Regardless, frequent medical check-ups are essential.
How congenital (from birth) aural atresia is dealt with depends on factors such as how many ears are affected, hearing ability, cosmetic preference, and the likelihood of restoring hearing. If both ears are affected, hearing tests will be failed, indicating the need for early use of hearing aids to amplify sounds. Meanwhile, some studies indicate that if only one ear is affected, it might still impact the child’s academic performance. Therefore, the decision to use a hearing aid can be controversial. This becomes especially complicated in places where these hearing aids need to be privately purchased and are not readily available, as the cost of the hearing aid could outweigh the potential benefits for the child.
Patients with this condition may need regular attention from teachers and speech therapists to ensure their speech and language develop normally. Regular medical check-ups including hearing tests every 6 to 12 months are recommended to make sure the healthy ear remains so. Any middle ear infection should be treated promptly and aggressively.
In cases where both the pinna (external part of the ear) and the ear canal are underdeveloped, the timing for each repair surgery must be coordinated. Some surgeons recommend repairing the ear canal before the pinna, prioritizing restoring hearing over improving appearance. In contrast, others might suggest using a hearing aid until the child is old enough for a series of surgeries to fix both problems. Surgical treatment is generally postponed until the child is around 5 to 6 years old.
Before any surgery, patients could benefit from using bone-conducting hearing aids, which work by sending sound vibrations directly to the inner ear. The ideal age for surgical intervention for a child with hearing problems in both ears is also around 5 to 6 years of age. There are several reasons for this. One is to allow the structures involved in equalizing the pressure in the ear to mature and prevent complications related to the middle ear. Another reason is the improved understanding and cooperation from the child during recovery.
For cases where only one ear is affected, factors like the child’s speech, language, academic development, maturity level, and hearing ability in the healthy ear need to be considered. With a normal hearing healthy ear, some might delay surgery until the patient is old enough to participate in the decision for surgery.
There are different types of surgical treatments for this condition, depending on how severe it is. Lateral atresia is usually repaired with meatoplasty, a less severe condition is repaired with a canalplasty. The decision to proceed with these ear canal repair surgeries often depends on a grading scale that rates the chances of achieving close to normal hearing post-surgery. This grading considers several anatomical features, with higher scores indicating better chances of improved hearing post-surgery.
Some studies have shown that patients with higher scores had a higher chance of achieving near-normal hearing with surgery, while patients with lower scores had lower chances. Despite these statistics, people with a very low score might not be good candidates for ear canal repair surgery. The advantages of having surgery over using hearing aids include improved sound detection and better hearing in noise.
What else can External Ear Aural Atresia be?
When a doctor is diagnosing ear canal narrowing or aural stenosis, they’re also considering the congenital condition aural atresia. Congenital aural atresia, which is when the ear canal doesn’t form properly at birth, can be categorized in two ways:
- Nonsyndromic, which means it’s not connected to any other symptoms and often the cause is unknown.
- Syndromic, which is associated with a specific syndrome like Goldenhar syndrome, Treacher-Collins syndrome, Crouzon syndrome or others.
Goldenhar syndrome, also known as oculoauriculovertebral dysplasia or hemifacial microsomia, is one of the most common syndromes linked to aural atresia. This might happen because of an injury to a particular artery, leading to defects affecting the first and second parts forming the region of the throat and neck during development. This syndrome can cause a range of physical issues, including those affecting the face, heart, kidneys, spine, and nervous system. It’s often inherited from parents.
Treacher-Collins syndrome is a rare disorder that affects facial structure, causes hearing loss, and can lead to difficulties in breathing. This is important to diagnose early to manage the anesthesia, especially to prevent airway blockages during surgery. Crouzon syndrome, caused by genetic mutations, leads to changes in the shape of the skull, widely-set eyes, bulging eyes, a flat forehead, an unusual nose shape, underdeveloped midface, and sometimes aural atresia.
In addition, aural atresia can sometimes appear in people with Mobius syndrome, Klippel-Feil syndrome, Fanconi syndrome, DiGeorge syndrome, De Grouchy syndrome, branchio-oto-renal syndrome, and Pierre Robin syndrome.
What to expect with External Ear Aural Atresia
Predicting the outcomes for both types of hearing loss due to aural atresia, which can be either inherited or acquired later in life, is quite difficult. This is because it largely depends on how severe the condition is, as well as any related abnormalities. In most cases, the overall outlook for the future is positive.
In aural atresia, hearing loss is usually around a 40 to 60 dB level, which is nearing the maximum hearing loss due to an almost complete or complete blockage of the ear canal. The average hearing level after surgery is between 25 to 35 dB, which is considered as mild hearing loss, and allows for better distinguishing of sounds and where they are coming from.
Due to timely interventions, children can develop suitable hearing and speech skills; however, the hearing level may not be the same as that of normally developed ears. There is also a notable chance, nearly 40%, of the repaired ear canal becoming narrow again.
This largely depends on the cause of the atresia/narrowing. Long-term results are best in cases where the aural atresia that has developed is not due to autoimmune causes. In contrast, congenital or inherited atresia, especially when concurrent with autoimmune or genetic conditions, tends to have the worst prognosis.
In such cases, a surgical approach might be better, but only to remove the cholesteatoma, which is a skin cyst in the ear. For restoring hearing, bone-conduction hearing aids might be more beneficial.
Possible Complications When Diagnosed with External Ear Aural Atresia
If congenital aural atresia, a condition where the ear canal is underdeveloped or absent, isn’t treated, it can lead to serious problems like delayed language development and severe learning disabilities. People with narrow ear canals are also more likely to develop cholesteatomas, which are abnormal growths in the ear that may require surgery.
After surgery to repair aural atresia, some complications may occur. These include distortion of the tympanic membrane graft (part of the ear), narrowing of the ear canal again, dysfunction in the joint connecting the jaw to the skull, and paralysis of the facial nerve.
Additionally, some people may experience changes in taste, varying degrees of hearing loss, infections, and vertigo, also known as dizziness.
Common Complications:
- Delayed language development
- Severe learning disabilities
- Cholesteatomas
- Changes to the shape of the tympanic membrane graft
- Narrowing of the ear canal
- Dysfunction in the temporomandibular joint
- Facial nerve paralysis
- Taste disturbance
- Types of hearing loss
- Infections
- Vertigo
Recovery from External Ear Aural Atresia
A material known commonly as ‘packing’ is typically left inside the ear canal for about three weeks after certain types of ear surgeries. After surgery, it is recommended that patients undergo an ‘audiogram’, which is a type of hearing test, six to eight weeks later.
Preventing External Ear Aural Atresia
Congenital aural atresia, a condition where the ear canal is not properly formed at birth, often occurs randomly without a known gene fault. That’s why parents of patients should be reassured that the chances of the same problem happening in future pregnancies is no higher than for anyone else. It’s also crucial to understand the impact of hearing loss tied to this condition, and the significance of proper medical treatment. The patient, together with their family, following the doctor’s orders after surgery can lead to better results. Furthermore, regular check-ups at each stage are a must to prevent serious complications that can’t be fixed.
